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Foundation Cracks and Slopped Concrete floor

Hello everyone,
I'm trying to buy this house that appears to have some foundation issues. I've loaded some photos for you to see. The house is a semi-detached built in 1930. The cracked wall shown on the photos is the shared wall. There are large step & horizontal cracks. The issues appeared to be continuing since old cracks have been fixed and new cracks emerged. The wall doesn't appear bowing. The concrete floor however is also cracked and slopped/sagged significantly towards this wall. No evidence of water leakage. The opposite wall showing signs of normal settlements on the exterior brick with many small stepping cracks.
I was told by an architect that this is normal in old houses. I haven't consult with a structural engineer yet. I plan to redo the floor and fix the cracks without concerning about the underpinning. Please advise if this is something of a concern that I should get a structural engineer involved? Thank you so much for your help. Greeting from Toronto.

Re: Foundation Cracks and Slopped Concrete floor

Originally Posted by Cafetran

Hello everyone,
I'm trying to buy this house that appears to have some foundation issues. I've loaded some photos for you to see. The house is a semi-detached built in 1930. The cracked wall shown on the photos is the shared wall. There are large step & horizontal cracks. The issues appeared to be continuing since old cracks have been fixed and new cracks emerged. The wall doesn't appear bowing. The concrete floor however is also cracked and slopped/sagged significantly towards this wall. No evidence of water leakage. The opposite wall showing signs of normal settlements on the exterior brick with many small stepping cracks.
I was told by an architect that this is normal in old houses. I haven't consult with a structural engineer yet. I plan to redo the floor and fix the cracks without concerning about the underpinning. Please advise if this is something of a concern that I should get a structural engineer involved? Thank you so much for your help. Greeting from Toronto.

Difficult to make a diagnosis from here with a few pics. Cracks in concrete and block are not uncommon, but might indicate other problems. I have no experience in heaving from freeze/thaw (being in Calif.), so I would start with a home inspection and see what the inspector says.

Re: Foundation Cracks and Slopped Concrete floor

Thank you for trying to help out. The previous photos were taken by the home inspector. He suspected potential issues with the foundation but asked to bring in a structural engineer. I went to back to the house today and took some more photos. Also noticed that there are other cracks on some dry walls and potentially sagged ceiling on the main floor.
The strange thing is that when a horizontal cracks occurred at the sharing wall of a semi-detached, without trees or grounds to push against the wall. Here I've taken some more photos but couldn't load them today but will try again. I think I will have to bring in the engineer to check it out eventually. I'm hoping to hear some insight from your own experience.
Thank you again.

Re: Foundation Cracks and Slopped Concrete floor

You hired an inspector and received their recommendation that a structural engineer is needed. That inspector was there and supposedly, you vetted the inspector's qualification and experience. What more do you expect from us on a web site with a few poor quality pictures? Either walk away from the deal, buy the house "as is" with the known risk or bring in a structural engineer. Those are your options. Anything else is game playing.

Re: Foundation Cracks and Slopped Concrete floor

The stair-stepped cracks and the re-appearance of cracks indicates un-reinforced foundation walls and slab. There is no rebar to hold the walls or slab together. As stated previously, the photos don't tell the story very well so if you are serious about the house definitely have your engineer look at it, but, based on his/her recommendations, if the walls aren't bowing you could just live with it. That is, if you don't mind continually patching cracks when the house moves every spring and fall.

Re: Foundation Cracks and Slopped Concrete floor

Are the concrete blocks offset vertically along the face of the foundation walls in the basement and/or crawl space area? If so, this may indicate some lateral/inward or outward movement of the ground/soil adjacent to the foundation walls. I would recommend taking a 3'-0" level and placing it against the vertical areas on the foundation walls and checking for signs of significant + or - deflection.

Taking readings with a reliable (Delmhost or equivelant) moisture meter is also highly recommended to determine actual moisture levels in the foundation walls and adjacent construction materials.

Re: Foundation Cracks and Slopped Concrete floor

1. The wall has had previous repairs.
2. Repairs have cracked again.
3. Active movement.
4. No access to neighbouring common wall. What is going on with that side of the building.
5. A block house circa 1930 would not have had rebar installed.
6. The foundation of the common wall could have been built on disturbed soil or their is organic debris under the footing.
7. The crack on the floor could have resulted from subsidence of footing.

Since your inspector recommended further assessment by an engineer then that is your next step. You need to know if the settlement is active, or stable and what resultant cracking/settlement may have done to the load carry capabilities.

Re: Foundation Cracks and Slopped Concrete floor

Inadequate info to attempt to give specific advice, but one thing I have seen that MIGHT fit the conditions as I understand them (duplex partition wall, no backfill either side, no lateral displacement of the wall) is moisture-related seasonal expansion/contraction of the subgrade.

All (non-granular) soils expand and contract to some degree with wetting and drying. Obviously, some soils are very expansive and are labeled as such (expansive clay, or 'CH' in the lab, for example). But even less expansive, or normal soils, can cause some vertical displacement through seasonal wetting/drying. In a block wall, this can result in a horizontal gap along a mortar joint. Or, if the movement is uneven, stair-step cracks can result.

If you have stair-step cracking at or near the junction of the party wall with the front and rear walls, with the horizontal gaps more toward the middle, this would support this theory, since the moisture typically comes from the exterior and the exterior is also subject to more temperature fluctuation. The way the walls tie-in is also a factor.

Slabs can react similarly, or be carried along for the ride, which is why I like to ensure that a separation joint or expansion joint is always used in between structural and 'flatwork' concrete.

Anyway, the reported fact that there is evidence of repeated repairs indicate ongoing movement. In a newer house it could be "on-going (differential) settlement". In a house this age, all "settlement" (compression of soils due to static loading) has already occurred. My report would read "Structural movement of foundation at party wall resulting in both horizontal and stair-step cracking. No lateral displacement observed, but prior repairs indicate on-going or seasonal movement. Extent of cracking is not structurally significant; maintain repairs as needed."

Of course, that is a statement based on generalities, not your case, but I'd bet your engineer will say something similar.

Re: Foundation Cracks and Slopped Concrete floor

A test you can do is sounding the floors and walls. Take a hammer and go around the interior floors taping and sounding. if you have a large void under the floor you will soon know. The change in the sound is easy to understand.

Voids can be a big expense to fix. This will require a soil engineer.
not a structural engineer. these are not the same guys.

Did you get any soil reports on the property or any information form the contractor that completed the first repair?

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